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Permaculture Design Principle 5 – Using Biological Resources

The fifth Permaculture Design principle is ‘Using Biological Resources’.

This design principle is concerned with the use of biological resources to do work or conserve energy, rather than using non-renewable energy sources such as fossil fuel resources. Wherever we can use a plant or animal to perform a certain function in our designs, then this is our preferred approach.

For example, we can use livestock to keep grass short rather than use a lawnmower, or use plants that attract beneficial predatory insects to control pests rather than use toxic chemical pesticides.

It is critical to plan the use of biological resources early in the design process. You will need to figure which biological resources you wish to utilise on the site, and what your strategy will be to manage them. These biological resources will form the very basis of your energy recycling systems, and as a result, determine how sustainable your design will be.

To put it another way, biological resources are a key to recycling energy and materials, so the more you use them successfully, through a well planned strategy, the more sustainable your systems will be within your design.

It is important to point out at the beginning of this discussion, that even though we are looking to utilise natural resources in the place of less energy efficient non biological resources, we do not exclude the use of non biological resources if:


To provide an example of each, if our soil is so depleted that it cannot support any plant growth, we can responsibly use chemical fertilizer at the beginning to get our green manure plants growing, to commence the addition of organic matter and build soil fertility. The fertile soil will be a lasting biological system.

In the second case, we can use non-renewable fossil fuels to power earthmoving equipment, which we can use to build permanent physical infrastructure, such as dams and swales (contour trenches) for water harvesting and storage, and roads for access.


Practical Examples of the Use of Biological Resources

Listed below are various examples of using biological systems to create productive permaculture systems, while saving energy and resources – because we let nature do the work.


1. Using Biological Resources – Fertiliser

Conventional/unsustainable methodChemical Fertilizer – is either mined (as in the case of  potassium and phosphorus) or artificially synthesized using energy derived from fossil fuels (as is the case for synthetic nitrogen fertilizers). Both are unsustainable because mining of a finite resource is non-renewable, as is the fossil fuel consumed to manufacture synthetic nitrogen fertilizer.

Conventional/unsustainable issues:


Biological resource alternative:


In Nature, animals eat plant matter and produce manure, which provides nutrients to the plants. This is the fertilizer that plants evolved to utilise. Livestock can be kept to produces various resources, along with manure. Chickens and ducks produce eggs and meat, rabbits produce meat and they all produce manures which can be used to feed plants. On larger properties, greater numbers of livestock and/or larger livestock can be kept. On rural properties,  goats and cattle can be used to supply milk, and sheep can be kept for wool production, and these larger animals provide greater quantities of manure. Horses can be kept for recreation, transportation and will also provide manure. This ties in with the second Permaculture Design principle – ‘Each Element Performs Many Functions’.


Nitrogen Fixing Plants

Plants can also be used to add fertility to the soil. Nitrogen fixing plants have root nodules which contain the symbiotic  Rhizobium nitrogen fixing bacteria, which can take nitrogen from the air and convert it to a form usable by plants. This nitrogen fixing process in the root nodules helps the plant to grow, and when the plants drop their leaves, or when the roots die back (because the foliage is pruned), usable nitrogen is returned to the soil. Nitrogen fixing annual plants can also be grown as green manures, then cut down as soon as they begin to flower so they release all their nitrogen into the soil. If they are not cut down, the nitrogen goes into their beans, peas, etc.

The most common nitrogen fixing plants are the plants and trees from the family Fabaceae (bean and pea), which includes legumes such as alfalfa, beans, clovers, lupines, peanuts, peas, and leguminous trees, such as tagasaste (tree lucerne) and acacias.

Note, there are some members of the Fabaceae family which do no fix nitrogen, such as carob and honey locust trees.

Conversely, some non-leguminous species have the ability to fix nitrogen, such as alder, bayberry, casuarina, eleagnus as well as the tiny floating aquatic fern azolla (fairy moss).


Dynamic Accumulators

Dynamic accumulators are plants that have tap-roots which drill down into the deeper levels of the soil and ‘mine’ certain nutrients, which they accumulate within themselves. When these plants die down, the accumulated nutrients are release to the surface of the soil where they then become available to other plants.

Some common dynamic accumulator plants include comfrey, stinging nettle, borage, clover, dandelions, strawberries. lemon balm and yarrow.

Comfrey has nitrogen rich leaves, and can be used as a compost activator (as can yarrow). Comfrey leaves can be composted or fermented to produce a nutrient rich natural fertilizer.


Green Manures

Green manures are crops grown to supply organic matter and improve the soil. They are not harvested, but are cut down to form a mulch on the soil surface or dug into the soil just as the flowers start to form.

Green manures have many benefits, they can:


Plants which are used as green manures include:


2. Using Biological Resources – Pest Control

Conventional/unsustainable methodChemical Pesticides– highly toxic synthetic poisons derived from petrochemicals/fossil fuels.

Conventional/unsustainable issues:


Biological resource alternative:

Beneficial Predators – Insects

Rather than trying to control pests, we can create an environment that attracts predators of pests, which will eliminate the pests for us naturally.

Beneficial predatory insects can be attracted to the garden by planting plants that provide them with:


The main plants that appear to attract and and provide a rich nectar and pollen source for beneficial insects belong to the Umbelliferae (parsley) and Compositae (daisy) families.

The Apiaceae (formerly Umbelliferae) family are characterised by umbrella-shaped clusters of small 5-petalled flowers, which form a large flat head of white or yellow flowers. Plants from this family include angelica, anise, carrots, caraway, celery, coriander, cumin, dill, fennel. lovage, parsley, parsnip  and  Queen Anne’s Lace.

The Asteraceae (formerly Compositae ) family are characterised by disk-like flower heads made up of “composites” of many tiny flowers growing together, arranged like rays around a centre. Plants from this family include asters, calendula, cosmos, dandelions, daisies, sunflowers, tansy, yarrow and zinnia.

The most popular ones are any type of mustard plant, as well as other early blooming nectar and pollen sources, like buckwheat, coriander, red clover, and legumes like vetches

These plants flower over a long period of time, and provide a steady and abundant flow of nectar and pollen for the beneficial predatory insects, which extends their lifespan, and allows them to lay more eggs, and consume more pests.

In addition to these families of plants, beneficial predatory insects need a permanent shelter, so it is important to have perennial plants in the garden to give them a home all year round and to provide over-wintering locations. Include ground cover plants, low herbaceous plants and shrubs create a good habitat.

The beneficial predatory insects attracted by these plants include Ladybirds, Lacewings, Hover flies, Parasitic wasps.

Other beneficial insects which also consume garden pests are Dragonflies, Praying Mantis and Spiders


Beneficial Predators – Other

There are many other species that consume garden pests :


3. Using Biological Resources – Erosion Control

Plants can be used to stabilise exposed soil to prevent erosion. In fact Nature does this automatically with pioneer plants (often erroneously called “weeds”). These plants will cover any bare patch of soil to stabilise it, and commence the first step in ecological forest succession which will ultimately turn the area (if possible) into a stable climax forest.

We can use various plants and trees for erosion control:


4. Using Biological Resources – Fire Control

A fire barrier can be constructed using fire retardant and resistant plants and trees – a shelter belt, which  is a wide strip of deciduous fire resistant trees and plants that can shield the house from radiant heat, and catch wind blown burning embers.

Trees suitable for this purpose are typically European deciduous trees, such as deciduous fruit and shade trees.

A selection of suitable trees includes:

A shelter belt can be planted at the boundary of the 30m perimeter between the house and the surrounding forest or wilderness.

(Note: An extensive list of fire retardant/resistant plants and trees can be found in the Permaculture Principles article 3. Each Important Function is Supported by Many Elements)


5. Using Biological Resources – Tillage

Tillage is the term used to describe the agricultural preparation of the soil by digging it and turning it over.

The soil is a very complex ecosystem, filled with a diverse range of soil life that is critical for plant growth and health. Digging and turning over the soil exposes a very delicate ecosystem to the air which dries it out, and to the ultraviolet rays of the sun, which sterilize the soil – killing the soil organisms. The soil loses a lot of its nutrients, such as carbon and nitrogen It also loses a lot of its organic matter, and as a consequence, does not retain water as well. The delicate soil structure is destroyed, compaction of soil occurs, leading to hardpan formation, and reduced water infiltration in the soil, and more surface runoff, which increases soil erosion.


Biological resource alternative:

No-dig gardening

In Nature, soil does not to be manually cultivated for spectacular forests to grow. What holds true in Nature also holds true in the garden. In a forest, organic matter in the form of fallen leaves, twigs and braches, annual plants at the end of their yearly cycle and other plants at the end of their lives are all deposited on the forest floor when they decompose into rich humus.

We can add organic matter directly to the soil surface, such as manure, compost, straw, leaves etc. Garden waste such as prunings from trees and shrubs can be fed into a mulcher to be broken down into small pieces, and then spread over the soil as a mulch. Adding a layer of organic matter over the soil, in a layer approximately 5cm-15cm (2”-6”) thick is in effect ‘sheet composting’, where the garden beds become large composting areas. By the action of earthworms, bacteria, fungi and insects, the organic matter is slowly broken down and released into the soil, providing nutrients to the garden. Because the soil is not disturbed, a stable soil ecosystem is created, and plant health is improved. Moisture is also better retained due to the mulching, and the organic matter in the soil works like a sponge to better retain the moisture in the soil. The mulching also prevents soil erosion, stops runoff of rainwater across the surface, and assists the rainwater to percolate into the soil. The earthworms will create channels in the soil, which will help both water and air to penetrate into the soil.

With no-dig gardens, the soil is not compacted because it is not walked upon. Stepping on the soil destroys the soils structure by compacting it, preventing air and water penetration to the plants roots, which affects plant health, restricts plant growth and reduces productivity.


Chop and Drop

In Nature, when plants die down, they stay in the same place. They’re not uprooted and disposed of! Do not uproot annuals that have finished producing at the end of the season, cut the stem at soil level. The roots will rot away to create thousands of intricate air and water channels in the soil that you could never manually replicate. The tops of the chopped down plants can either be laid down whole, or chopped into smaller pieces to speed up their breakdown, to create a natural sheet compost system like the forest floor


Animal tractors

In permaculture, we always use the best and most (energy) efficient resource for each task. In the same way that we can use earthworms to do our digging, because earthworms dig much better than we do, we can also use animals to weed, fertilise and clean up the garden. An animal tractor is a movable enclosure in which animals are placed so that they can scratch, dig, eat weeds,and manure the soil. The enclosure ids left in an area long enough for the animals to do their work, and then moved to a new area. It is not left permanently in one area because excessive soil disturbance will result.

Many animals can be used in animal tractors. The most common are chicken because they scratch, dig, eat weeds and pest insects, and manure the ground very well. Other suitable animals are rabbits, guinea pigs, ducks, geese, turkeys,pigs and goats.


These are just some of the possible practical examples of where biological resources can be used in place of non-renewable energy sources to do work in a Permaculture system, the possibilities are almost endless. Considering that Nature grow all plant life quite well without human assistance or intervention, by looking at how Nature achieves this, we can recreate the same energy efficient systems in our Permaculture designs.

The examples not only show how using biological systems is a more energy efficient practice than using non-renewables such as fossil fuels, but how the use of these non-renewables actively cause extensive damage to ecosystems of which we are a part, ultimately causing harm to ourselves and all other species. So, it is quite evident that using biological resources in our designs not only save energy, but save the planet!



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